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Julian Sutton (2022)
Sutton, J. (2022), 'Magnolia rostrata' from the website Trees and Shrubs Online (treesandshrubsonline.
Deciduous tree to 25 m. Bark pale grey. Branchlets stout, 7–14 mm in diameter, green with reddish-brown hairs when young; axillary vegetative buds grey-green, terete, glabrous. Leaves in clusters of 7–9 at branchlet apex. Leaf blade strikingly large, thickly papery, obovate, 34–50 × 21–23 cm; lower surface glaucous with red-brown curved hairs; upper surface glossy green; secondary veins 28–30 on each side of midvein; base broadly cuneate to cordate; apex rounded, shortly acute, or sometimes bifid. Petiole strong and thick, 4–7 cm, hairy at first; stipular scar prominent, nearly ⅓–⅔ as long as petiole. Flowers fragrant, emerging after the leaves, 8–9 cm across. Tepals 9–12; tepals of outer whorl greenish below, pink above, oblong-elliptic, 8–13 × ~5.6 cm, reflexed; tepals of inner 2 whorls white, obovate-spoon-shaped, 12–14 cm, erect, base clawed. Stamens purplish red; filaments ~5 mm; connective exserted and forming a triangular mucro; anthers ~1 cm. Gynoecium cylindric. Fruit terete, 11–20 × ~4 cm, erect, base broadly rounded, apex gradually narrowing; mature carpels with a 5–8 mm curved beak. Seeds about 7 × 5 mm, flat. Flowering May–July (China), June (UK); fruiting September–October (China). (Xia, Liu & Nooteboom 2008; Chen & Nooteboom 1993).
Distribution Myanmar NE China SE Xizang (Mêdog), W Yunnan
Habitat Broad-leaved forests; 2100–3000 m.
USDA Hardiness Zone 7-9
RHS Hardiness Rating H4
Conservation status Endangered (EN)
This deciduous species has impressively large leaves with a parchment-like texture, glaucous beneath, clustered towards the shoot tips in false whorls, but disappointingly small flowers. As a foliage plant Magnolia rostrata rivals the effect of M. macrophylla. It suits milder parts of our area.
M. rostrata has the most westerly range of the the three Asiatic species in Section Rhytidospermum. It differs from M. obovata and M. officinalis in its smaller, less strongly scented flowers; its apparently sometimes drooping fruits with long-beaked carpels; and the red-brown hairs on the midrib and veins on the leaf underside. The American M. tripetala is usually a smaller, more shrubby plant with even larger leaves, and malodorous flowers.
It came to scientific attention in the early 20th century. George Forrest first collected it in Yunnan, 1917, with Farrer (Myanmar) and Kingdon-Ward (Myanmar–Xizang border) collections following. Its early taxonomic history was plagued by confusion with M. campbellii: these first collectors confused the two, and the original publication (Smith 1920) described the shoots of M. rostrata but the flowers of M. campbellii, those of M. rostrata appearing much later in the year and less conspicuously. Smith’s specific epithet refers to the long carpel beak. While the species’ range appears as a broad arc on the map, it exists only in scattered, fragmented populations threatened by overexploitation of the bark, which is used for medicine in the same way as M. officinalis (IUCN 2021).
The erect, very stout and little-branched shoots of M. rostrata give it a gaunt appearance in winter. In cultivation it tends to produce a single leader with few short stubby side branches, or a few competing leaders. The petiole scars which encircle its stems are remarkably persistent, still visible on mature trunks. Branches are brittle and easily damaged by wind, as are the huge leaves when still young and soft (Treseder 1978). Mild, reasonably sunny but very sheltered conditions are required for it to look its best; at Trewithen, Cornwall, the top of a large specimen began to grow ‘outwards rather than upwards’ when it outgrew its shelter (G. H. Johnstone in Arnold-Forster 1948). Moist but well drained soil is ideal. The small, summer flowers with a faint melon-like scent are of little horticultural significance; occasional trees with pink tepals have been noted. However, the fruits with masses of very small, bright red seeds can be striking. By maturity the distinctive carpel beaks become curved and spiny. At least in cultivation, there seems to be variation in how the mature cones are held. In some, for example a tree at Caerhays Castle (C. Williams pers. comm. 2022) they remain erect – see also the image below from Glenarn Gardens. However, Treseder (1978) seems ambiguous on the point, mentioning both erect cones and a habit of drooping later: see the image below of a plant with pendent cones at Borde Hill. Botanical literature seems not to adress the issue, and further study is required
The species entered Western cultivation through the 20th century collectors mentioned above; it had flowered in Britain by 1935. Good British specimens are mostly on the western fringes, including trees at Castle Kennedy, SW Scotland (one measured 12 m × 116 cm in 2019) and Tregrehan, Cornwall (including 13 m × 92 cm, 2016), although there is a specimen in the Valley Gardens, Windsor Great Park (9.5 m × 68 cm, 2021 – The Tree Register 2021). An exceptionally large specimen at Sidbury Manor, Devon (20 m × 138 cm, 1990) is now gone.
It is rarely seen in Europe outside the British Isles; there is a young example at Arboretum Provinciaal Domein Bokrijk, Belgium (Plantcol 2021). Extremely rarely seen in North America, it is in the New Zealand nursery trade.